System and process for monitoring myocardial integrity

Abstract

A process and apparatus for providing an electrophysiologic indicator of reversible myocardial ischemic injury as well as a procedure and apparatus for providing a method of assessing the status of myocardial preservation during elective cardioplegic arrest in order to assure complete electromechanical arrest from the onset of the application of the standard cardioplegic techniques. The procedure for establishing an indication of reversible myocardial ischemic injury involves implanting multiple electrodes in the myocardial tissue and sensing the instantaneous unipolar electrical potentials of the electrodes and comparing those sensed potentials with a series of registered potentials for healthy tissue. The procedure and apparatus for assessing the status of myocardial preservation involves the use of the same implanted multiple electrodes which are placed in the ventricle and the apparatus provides for a sensing and documenting of ventricular electrical activity in the visually arrested heart at a time when a peripheral EKG would be quiescent in order to detect persistent activity originating in the lower atrial septum and conducted through the AV node to the ventricles at what was previously considered to be safe myocardial temperatures.

What is claimed as new and desired to be secured by Letters Patent of the United States is: 
     
       1. A process for the on-line monitoring of the viability of myocardial tissue of a patient during and after a surgical procedure comprising the steps of: implanting multiple electrodes in said tissue prior to said surgical procedure;   sensing the instantaneous unipolar electrical potentials of said electrodes prior to said surgical procedure;   registering the peak-to-peak voltage values of said instantaneous unipolar electrical potentials for a period of time occurring prior to said surgical procedure for each of said electrodes which have a negative slope exceeding a predetermined value   performing said surgical procedure;   sensing the instantaneous unipolar electrical potentials which have a negative slope exceeding said predetermined value of each of said electrodes during and after said surgical procedure;   comparing said registered values for each of said electrodes with said sensed potentials during and after surgery for each of said electrodes; and   providing an output indication of injured tissue when said registered values exceed said sensed potentials during and after surgery by a predetermined amount for at least one of said electrodes.   
     
     
       2. A method according to claim 1 wherein said multiple electrode are plunge electrodes each containing at least one intramural unipolar contact electrode wherein one of said plunge electrodes is implanted in the right ventricle, wherein a second of said plunge electrodes is implanted in the anterior left ventricle, wherein a third of said plunge electrodes is implanted in the lateral left ventricle and wherein a fourth one of said plunge electrodes is implanted in the posterior left ventricle. 
     
     
       3. A method according to claim 2 wherein said second, third and fourth plunge electrode each contain five intramural contact unipolar electrodes. 
     
     
       4. An apparatus for the on-line monitoring of and displaying of the viability of myocardial tissue comprising: a plurality of electrodes suitable for implantation in said myocardial tissue;   means for sensing the instantaneous electrical potentials of each of said electrodes including a gain control means and a slope detector means wherein said sensing means outputs an amplitude measurement signal when the slope of said instantaneous sensed potential of said electrodes exceeds a predetermined negative value;   means for storing the peak-to-peak amplitude of said signals output from said sensing means for each of said electrodes during a controlled period when said plurality of electrodes are implanted in said myocardial tissue and said myocardial tissue is determined to be healthy tissue;   means for comparing the peak-to-peak amplitude of said signals output from said sensing means with said stored amplitudes wherein said comparator means outputs an indication signal indicating injured tissue when the output of said sensing means is less than a predetermined fraction of said stored values for at least one of said electrodes.   
     
     
       5. An apparatus according to claim 4 wherein said predetermined negative value is 0 and said control time period is 0 and further including a display means for displaying the outputs of said sensing means. 
     
     
       6. An apparatus according to claim 4 wherein said plurality of electrodes comprise a plurality of plunge electrodes each containing at least one intramural unipolar contact electrode. 
     
     
       7. The apparatus according to claim 4 wherein said sensing means further includes a sample and hold circuit for receiving the output of said gain control means and said slope detector means and wherein said sensing means further includes a first delay means connected between the output of said slope detector and said sample and hold means in order to provide for blocking of a subsequent retriggering of said sample and hold circuit during a first predetermined time and a second delay means connected between said slope detector means and said sample and hold circuit in order to provide for a delay of the output of said sample and hold circuit by a second predetermined time in order to provide for continued digitization of signals after a first occurring signal. 
     
     
       8. An apparatus according to claim 7 wherein the output of said sample and hold means is fed to a analog to digital converter with the output of said analog to digital converter providing an 8 bit serial-parallel output to an address generating means. 
     
     
       9. An apparatus according to claim 8 wherein the output of said address generator means is converted by an output circuit means to provide said sensing means outputs and wherein said sensing means outputs are interfaceable with a digital computer. 
     
     
       10. A process for accessing the status of myocardial preservation during cardioplegic arrest in order to assure complete electromechanical arrest from the onset of the application of standard cardioplegic techniques, comprising the steps of: implanting multiple electrodes in the ventricle of the heart of a patient prior to the initiation of standard cardioplegic techniques;   sensing and recording the output of said multiple electrodes prior to the application of standard cardioplegic techniques;   applying standard cardioplegic techniques to said patient;   sensing and recording the output of said multiple electrodes during the application of said cardioplegic techniques; and   providing an output indication of the persistent ventricular activity when signals are sensed during the application of said cardioplegic techniques.